Insects and Their World
Grade 2 · Science · Study Guide
Insects are the most common animals on Earth! Learn what makes an insect an insect and how they live.
Insects are animals with six legs, three body parts, and an exoskeleton — a hard outer shell instead of bones inside. The three body parts are the head, thorax, and abdomen. Most insects also have two antennae and many have wings. Ants, butterflies, bees, beetles, and grasshoppers are all insects.
Insects grow and change through a process called metamorphosis. Some insects like butterflies and moths go through complete metamorphosis with four stages: egg, larva (caterpillar), pupa (chrysalis), and adult. Other insects like grasshoppers go through incomplete metamorphosis with only three stages: egg, nymph, and adult.
Insects are incredibly important to our world. Bees and butterflies pollinate flowers, which helps plants make fruits and seeds. Ants and beetles break down dead plants and animals, recycling nutrients back into the soil. Without insects, our ecosystems would fall apart! Even though some insects can be pesky, they are essential to life on Earth.
| Type | Stages | Example Insects |
|---|---|---|
| Complete metamorphosis | Egg → Larva → Pupa → Adult | Butterfly, moth, beetle, bee |
| Incomplete metamorphosis | Egg → Nymph → Adult | Grasshopper, cricket, dragonfly |
Key terms
- insect
- An animal with 6 legs, 3 body parts (head, thorax, abdomen), and an exoskeleton
- exoskeleton
- A hard outer covering that protects an insect's body (instead of bones)
- metamorphosis
- The process of an insect changing form as it grows
- larva
- The second stage of complete metamorphosis — like a caterpillar
- pupa
- The third stage of complete metamorphosis — like a chrysalis
- pollination
- Moving pollen from flower to flower, helping plants reproduce
Flashcards
- Insect
- Animal with 6 legs, 3 body parts, and an exoskeleton
- Exoskeleton
- Hard outer shell that protects an insect instead of bones
- Metamorphosis
- The process of changing form as an insect grows
- Larva
- Worm-like second stage of complete metamorphosis (e.g., caterpillar)
- Pupa
- Resting third stage of complete metamorphosis (e.g., chrysalis)
- Pollination
- When insects carry pollen between flowers to help plants reproduce
Practice questions
How many legs does an insect have?
- Four
- Six
- Eight
- Ten
Show answer
Answer: Six
All insects have exactly six legs — this is one of the defining features of an insect.
Spiders are insects because they have six legs.
Show answer
Answer: False
Spiders have eight legs, not six. Spiders are arachnids, not insects.
The hard outer covering of an insect is called an ___.
Show answer
Answer: exoskeleton
An exoskeleton is the hard outer shell that supports and protects an insect's body in place of internal bones.
What are the four stages of complete metamorphosis in order?
- Egg, adult, pupa, larva
- Egg, larva, pupa, adult
- Larva, egg, adult, pupa
- Nymph, egg, pupa, adult
Show answer
Answer: Egg, larva, pupa, adult
Complete metamorphosis has four stages in this order: egg, larva (caterpillar), pupa (chrysalis), adult (butterfly).
Bees help plants by carrying pollen from flower to flower.
Show answer
Answer: True
As bees visit flowers to collect nectar, pollen sticks to their bodies and transfers to other flowers, enabling plant reproduction.
Fun facts
- There are more than 1 million known species of insects — they make up more than half of all known animals!
- A honeybee visits up to 2,000 flowers to make just one jar of honey!
- An ant can carry 50 times its own body weight — like a second grader carrying a small car!
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